X-linked recessive mitochondrial myopathy is a rare condition caused by defects in the APOO gene, which codes for the MIC26 protein. Faulty MIC26 disrupts the insertion of the MICOS complex into the inner mitochondrial membrane, a vital step for proper cell energy production. When mitochondria do not work correctly, it can affect many different parts of the body. People with this condition may experience symptoms such as lactic acidosis, cognitive impairment, and features associated with autism. Studies using model organisms like yeast and flies have helped scientists understand that a failure in inserting the MICOS complex into the mitochondrial membrane underlies these problems. Though research has clarified some aspects of the disease mechanism, more work is needed to fully understand its impact on overall health.

Common symptoms in people with this condition include lactic acidosis, which is an increase in lactic acid levels in the blood, cognitive impairment that may affect learning and memory, and features seen in autism. These symptoms occur because the normal function of mitochondria, the cell's energy producers, is disrupted.

The condition is caused by defects in the APOO gene. This gene is responsible for making MIC26, a component of the MICOS complex. When there are defects in APOO, the MICOS complex cannot be properly inserted into the inner mitochondrial membrane, leading to reduced mitochondrial function. Studies in yeast and flies have provided evidence that these genetic issues contribute to the symptoms observed in this disease.